Locking device



1968 v. w. GURZENIDA 3,362,040

LOCKING DEVICE Filed July 25, 1966 VERNON W. GURZENDA INVENTOR wwffiwTTORNEYS United States Patent 3,362,040 LOCKING DEVICE Vernon W.Gurzenda, Somerset, Pa., assignor to Rockwood Manufacturing Company,Rockwood, Pa., a corporation of Pennsylvania Filed July 25, 1966, Ser.No. 567,550 Claims. (Cl. 1686) The present invention relates to animproved locking device, and more particularly to a tamper-proof lockingdevice which cannot be opened without destruction of the apparatus whichhouses the locking device.

In many applications, it is desirable that means he provided to preventtampering or unauthorized disassembly of the apparatus in question. Forexample, it is known that people are prone to remove objects such asdoor stops from motels, public buildings and the like.

It is a primary object of the pesent invention to provide an improvedlocking device.

Another object of the present invention is to provide apparatuscomprising an improved tamper-proof locking device which is of simpleconstruction.

Still another object of the present invention is to provide an improveddoor stop having locking means to prevent removal of the door stop fromthe surface to which it is attached.

In a broad aspect, the present invention comprises a pair ofcooperating, relatively rotatable members, said members cooperating toform an internal chamber, a spring detent secured to one of saidmembers, the other of said members having cam means adapted to compressthe spring detent upon relative rotation of the two members, and recessmeans provided in the cam surface. Upon continued relative rotationbetween the two members, the compressed spring detent upon reaching thevicinity of the recess expands into the recess to prevent furtherrelative movement between these members and to prevent disassembly ofthe apparatus.

The above and other objects, features, and advantages of the inventionwill become more apparent as this description proceeds.

In the drawings:

FIGURE 1 is a perspective view of a door stop in accordance with thepresent invention;

FIGURE 2 is a vertical cross-sectional view showing the door stop ofFIGURE 1 attached to a supporting surface;

FIGURE 3 is a view illustrating the relationship between a base platewhich carries the spring detent and a housing member which is providedwith internal cam surfaces which cooperate with the spring detent whenthe housing is placed in position upon the base plate and rotatedrelative thereto; and

FIGURE 4 is a view partly in section taken along a section linesubstantially perpendicular to the section illustrated in FIGURE 2.

Referring now to the drawings, and more particularly to FIGURE 1, thereis illustrated a door stop having a housing generally designated byreference numeral 10, and a resilient bumper 12 which is secured withinan upstanding annular projection 14 of the housing.

FIGURE 2 illustrates the door stop secured to a supporting surface 16such as a wall or door. The housing has a cylindrical wall 18 with oneend thereof abutting the surface 16 to form a completely enclosedinternal chamber 20. The door stop is secured to the wall by means of ascrew 22 which extends through an aperture 24 in a base plate 26 whichabuts the surface 16. The screw has a head 28 which fits into acylindrical opening 30 in the rear of surface of bumper 12. The plate 26may have projections 32 which extend into surface 16, or other suitablemeans, for preventing rotation of the plate relative to surface 16.

As is best show in FIGURE 3, plate 26 has a pair tapering configurationare positioned on the inner surface with apertures through which ends 36of a spring detent 38 project. In the illustrated embodiment, the springdetent 38 is generally semi-circular in cofiguration and its ends arenormally biased outwardly. The lugs 34 function as stops to maintain thespring detent in a compressed condition.

A pair of opposed cam surfaces 40, 42 of arcuately taperingconfiguration are positioned on the inner surface of the cylindricalwall 18. Preferably, the cam surfaces are integral with the wall 18. Alocking recess 44 is machined out of each cam surface, with the tworecesses being essentially at opposite ends of a diameter line drawnthrough the center of the device. The function of the recesses 44 willbe described hereinafter in connection with the procedure forassemblying the door stop.

In assemblying the door stop, the plate 26 is secured to surface 16 byscrew 22. With the spring detent 38 positioned as shown in FIGURE 3, theportion of the device shown at the right hand side of FIGURE 3 is placedupon plate 26 with the lugs 34 and the spring detent 38 ex tending intochamber 20'. The normal distance between the outermost tips of thespring detent ends 36 is slightly smaller than the diameter of chamber20. The housing 10 is now rotated relative to plate 26 in a clockwisedirection until the ends 36 of the spring detent contact the leadingfaces of the cam surfaces 40, 42. Further rotation of the housing causesthe ends of the spring detent to be pressed inwardly towards each otherby the cam surfaces so that the spring detent is compressed. When theends of the spring detent come into alignment with the locking recesses44, the spring detent ends 36 snap outwardly into recesses 44 topermanently lock the housing 10 to plate 26.

Although the locking assembly of the present invention has beendescribed for purpose of illustration as embodied in a door stop, itwill be appreciated that the locking mechanism may find utility in otherstructures where it is useful to substantially permanently secure oneportion of a device to another. Furthermore, various changes in theconfiguration of the spring detent may suggest themselves to those ofordinary skill in the art upon consideration of the present disclosure.For example, one end of the spring detent might be permanently fastenedin which case only one recess 44 would be employed. In view of theforegoing, it is intended to encompass all such changes andmodifications as fall within the scope of the appended claims.

What is claimed is:

1. Apparatus comprising a pair of cooperating relatively rotatablemembers, a spring detent secured to one of said members, a cam surfaceprovided on the other of said members and positioned to compress saidspring detent upon relative rotation between said members when in theoperating position thereof, a locking recess provided in said camsurface and positioned to be in alignment with an end of said springdetent and to receive said end upon expansion of the compressed springdetent into said recess, and means to enclose said spring detent in itslocked position to prevent access to said spring detent.

2. Apparatus according to claim 1, wherein said other member comprises ahousing having a wall portion disposed about said spring detent.

3. Apparatus according to claim 2, wherein said cam surface is integralwith the inner surface of said wall.

4. Apparatus according to claim 2, wherein said housing includes anupstanding annular projection, and fur- 3 ther comprising a resilientbumper secured within said projection.

5. Apparatus according to claim 1, further comprising a pair of opposedapertured lugs secured to said one member, said spring detent having itsends disposed within the apertures in said lugs, and said lugsconstituting stops limiting the outward expansion of said spring detent.

6. Apparatus according to claim 1, further comprising means to maintainsaid spring detent in a normally compressed condition.

7. Apparatus according to claim 6, wherein said one member comprises asubstantially flat plate.

8. Apparatus according to claim 7, further comprising a support surface,and means to secure said plate to said support surface.

9. Apparatus according to claim 7, wherein said means for maintainingthe spring detent in a compressed con- References Cited UNITED STATESPATENTS 334,819 1/1886 Stoddard 292-353 1,847,228 3/1932 Smith 292256.652,899,703 8/1959 Johnson 16 86 3,050,770 8/1962 Morse et al. 16-86 BOBBYR. GAY, Primary Examiner.

J. L. KOHNEN, Assistant Examiner.

1. APPARATUS COMPRISING A PAIR OF COOPERATING RELATIVELY ROTATABLEMEMBERS, A SPRING DETENT SECURED TO ONE OF SAID MEMBERS, A CAM SURFACEPROVIDED ON THE OTHER OF SAID MEMBER AND POSITIONED TO COMPRESS SAIDSPRING DETENT UPON RELATIVE ROTATION BETWEEN SAID MEMBERS WHEN IN THEOPERATING POSITION THEREOF, A LOCKING RECESS PROVIDED IN SAID CAMSURFACE AND POSITIONED TO BE IN ALIGNMENT WITH AN END OF SAID SPRINGDETENT AND TO RECEIVE SAID END UPON EXPANSION OF THE COMPRESSED SPRINGDETENT INTO SAID RECESS, AND MEANS TO ENCLOSE SAID SPRING DETENT IN ITSLOCKED POSITION TO PREVENT ACCESS TO SAID SPRING DETENT.